#include <stdio.h>
int main()
{
    int a = 1;
    int b = 2;

    switch(a)
    {
        case 1: b++;
        case 2: a++;
        case 3:
            switch(a)//switch可以嵌套使用
            {
                case 1: a++;
                case 2: b++; a++;
                break;
            }
            case 4:
            b++; 
            break;

    }
    printf("a = %d b = %d", a, b);//双参数用逗号和空格 隔开
    return 0;
}